Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

New cationic 99Tc/99Tc complexes formed with various symmetrical and asymmetrical vicinal dioximes of different carbon chain length (C5-C8) were synthesized by reduction of pertechnetate with BH4-, separated by HPLC and characterized by i.r./u.v./vis. spectroscopy, FAB mass spectrometry and electrophoresis. All complexes studied are trisdioximes containing boron as a constituent. Their lipophilicity, as assessed by the octanol/saline partition coefficient, ranges over almost four orders of magnitude. The myocardial uptake of the 99mTc complexes in mice proves to be lower than expected. The organ distributions are distinctly affected by the lipophilicity, the position of the dioxime group and the introduction of a terminal methoxy group.
 ...
PMID:Preparation, characterization and biological evaluation of cationic 99Tc/99mTc-dioxime complexes. 848 91

A series of asymmetrically substituted dodecafluorinated phthalocyanines has been synthesized via the Kobayashi ring expansion reaction of the corresponding dodecafluorinated boron subphthalocyanine with differently substituted 1,3-diiminoisoindolines. The mild reaction conditions employed during this ring expansion reaction gave rise exclusively to 3:1 asymmetrically substituted dodecafluorinated phthalocyanines. Metal insertion into the metal-free phthalocyanines was accomplished by heating at 40 degrees C in N,N-dimethylformamide in the presence of zinc bromide. The resulting zinc dodecafluorophthalocyanines were formulated as Cremophor EL oil-water emulsions and evaluated as photosensitizers in vitro against EMT-6 mouse mammary tumor cells. As compared to the previously studied zinc hexadecafluorophthalocyanine, these new asymmetrical zinc dodecafluorophthalocyanines exhibited improved photodynamic activity.
 ...
PMID:Synthesis and photodynamic activity of novel asymmetrically substituted fluorinated phthalocyanines. 1617 94

A new nanotube structural form is reported that resembles a double helix in multiwall boron nitride nanotubes (MW-BNNT) grown by a carbon-free chemical-vapor-deposition process as documented by evidence obtained by transmission electron diffraction and microscopy. The double-helix structure is found in MW-BNNTs exhibiting the same chirality in its different walls. The MW-BNNTs deviate from the structure of ideal nested coaxial cylindrical tubes. Most significantly, bright- and dark-field electron imaging reveals regular zigzag dark and bright spots on the side walls of the nanotubes. The repeating distance between the bright, or dark, spots is related to the chiral angle of the nanotube. Electron diffraction patterns recorded from individual nanotubes show additional diffraction spots belonging to the 201 zone axes, which are not allowed in a perfectly cylindrical nanotube. These additional diffraction spots become asymmetrical as smaller sections of the nanotube are probed. A series of diffraction patterns recorded along the tube axis showed that the imperfections giving rise to these spots move in a regular fashion around the circumference of the tube. It is shown that all experimental evidence supports the structure model of two helices; one is polygonal in cross section and highly crystalline and the other is circular and less ordered. It is further suggested that the double-helix structure is a result of stronger wall-wall interactions associated with the ionic bonding in boron nitride.
 ...
PMID:Double-helix structure in multiwall boron nitride nanotubes. 1624 2

A three-dimensional anionic framework built up from [ZnO4] tetrahedra and planar [BO3] groups, stabilized by H atoms, has been found for hydrogen zinc oxide borate, H[Zn6O2(BO3)3]. Boron and one of the borate O atoms are on 18e (2) positions. Triple units of [ZnO4] tetrahedra sharing a common oxygen vertex on a 12c (3) site and strong asymmetrical linear hydrogen bonds with the H atom [on a 12c (3) position] disordered over a twofold axis are specific structural features of this zincoborate. There is evidence that the reported Zn4O(BO3)2 [Harrison, Gier & Stuky (1993). Angew. Chem. Int. Ed. Engl. 32, 724-726] corresponds to this structure.
 ...
PMID:Proton-stabilized three-dimensional anionic framework in H[Zn6O2(BO3)3]. 1714 84

Stripping voltammetric determination of purine bases in the presence of copper ions at mercury, amalgam, or carbon-based electrodes has recently been utilized in analysis of DNA or synthetic oligodeoxynucleotides (ODNs). Here we report on copper-enhanced label-free anodic stripping detection of guanine and adenine bases in acid-hydrolyzed DNA at anodically oxidized boron-doped diamond electrode (AO-BDDE). The AO-BDDE was successfully applied in a three-electrode microcell in which an approximately 50 microL drop of the analyte solution can be efficiently stirred during the accumulation step by streaming of an inert gas. Accelerated mass transport due to the solution motion in the presence of copper resulted in enhancement of the guanine oxidation signal by about 2 orders of magnitude (compared to accumulation of the analyte from still solution not containing copper), allowing an easy detection of approximately 25 fmol of the ODNs. The proposed technique is shown to be suitable for a determination of purine (particularly guanine) content in DNA samples. Applications of the technique in magnetic bead-based DNA assays (such as hybridization with DNA sequences exhibiting asymmetrical distribution of purine/pyrimidine nucleotides between the complementary strands or monitoring of amplification of specific DNA fragments in a duplex polymerase chain reaction) are demonstrated.
 ...
PMID:Label-free sequence-specific DNA sensing using copper-enhanced anodic stripping of purine bases at boron-doped diamond electrodes. 1832 Oct 78

The use of nucleophilic and electrophilic processes allow the designed synthesis of several B-iodinated derivatives of o-carborane. Because of the straightforward Pd-catalyzed conversion of B-I to B-C bond with Grignard reagents, such as methylMgBr and biPhenylMgBr, both, symmetrical 3,6-R 2-1,2- closo-C 2B 10H 10 and asymmetrical 3-I-6-Me-1,2- closo-C 2B 10H 10 could be obtained. Not only conventional reactions in solution have been studied but also a highly efficient, clean and fast solvent-free procedure has provided successful results to regioselectively produce B-iodinated o-carborane derivatives by a careful control of the reaction conditions. The high number of nonequivalent leaving groups in boron iodinated o-carborane derivatives opens the possibility through B-C coupling to materials with novel possibilities and to self-assembling due to the enhanced polarizability of the C-H bond.
 ...
PMID:Designed synthesis of new ortho-carborane derivatives: from mono- to polysubstituted frameworks. 1863 Sep

The effects of the plasma expansion cup on the operation of a duoplasmatron ion source have been investigated by measuring the total ion current and the distributions of the ion energy, mass, and current density. A copper expansion cup did not affect the magnetic field near the anode of the ion source and consequently the ion current density distribution was sharply peaked near the center of the cup. Ion energy distributions were approximately symmetrical about anode potential. The dominant ionic species were D(+) (3) and D(+) at low and high arc currents, respectively. Changes in the electrical potential of the copper cup with respect to the anode produced negligible changes in the above data. A mild steel plasma expansion cup caused the magnetic field to diverge and intercept the cup walls, resulting in ion current density distributions that were flatter and more amenable to focusing than the ones with the copper cup. With the steel cup at anode potential, the ion mass distribution was similar to that from the copper cup; however, the ion energy distribution was asymmetrical about the anode potential with a peak about 10-20 V above anode potential. The total ion current from this mode of operation was about one-third the value from the copper cup. If the steel cup assumed floating potential, about 50 V below anode potential, the total current increased to the level observed from the copper cup and the ion energy distribution was similar to that observed with the copper cup but the current density distribution was much flatter than that of the copper cup. The ion mass distribution was 60%-70% atomic ions over the entire arc current range investigated. Based on these data, a modified plasma expansion cup was designed with tapered steel walls lined with a boron nitride insert. The overall performance of the duoplasmatron ion source with this cup was superior to any of the previous three modes of operation. The improved design uses a molybdenum anode insert which is far superior to copper in regard to erosion over extended operating times. A total beam current of 200 mA was produced at an arc current of 24 A.
 ...
PMID:Gas discharge ion source. I. Duoplasmatron. 1869 19

We report a first-principles based study of mesoscopic quantum transport in chemically doped graphene nanoribbons with a width up to 10 nm. The occurrence of quasi-bound states related to boron impurities results in mobility gaps as large as 1 eV, driven by strong electron-hole asymmetrical backscattering phenomena. This phenomenon opens new ways to overcome current limitations of graphene-based devices through the fabrication of chemically doped graphene nanoribbons with sizes within the reach of conventional lithography.
 ...
PMID:Chemically induced mobility gaps in graphene nanoribbons: a route for upscaling device performances. 1953 Jun 69

meso-Cyano boron-pyridyl-isoindoline dyes with asymmetrical structures were synthesized through a facile two-step reaction. Broad envelopes of intense vibrational bands were observed for the main spectral bands in the absorption and emission spectra. Moderate fluorescence quantum yields were obtained in solution, with significant intensity also observed in film, powder and crystal forms. An analysis of the structure-property relationships was carried out based on X-ray crystallography, optical spectroscopy, and theoretical calculations.
...
PMID:Synthesis and spectroscopic properties of novel meso-cyano boron-pyridyl-isoindoline dyes. 2519 56

In contrast to the well-recognized transverse-electric-field-induced half-metallicity in zigzag graphene nanoribbons, here, we demonstrate by first-principles calculations that zigzag graphene nanoribbons sandwiched between hexagonal boron nitride nanoribbons or sheets can be tuned into half-metal simply by a bias voltage or a moderate compressive strain. The half-metallicity is attributed to an enhanced coupling effect of spontaneous polarization and asymmetrical exchange correlation along the ribbon width. The findings should open a viable route for efficient spin-resolved band engineering in graphene-based devices that are compatible with the current technology of the semiconductor industry.
...
PMID:A New Paradigm to Half-Metallicity in Graphene Nanoribbons. 2629 62


1 2 Next >>